Hexachlorodisilane is ah important precursor for producing silicon and, for hydrogenation, derivatization, etc. Various methods are known for producing hexachlorodisilane.
There is a general problem with the known methods of production, however, in that hexachlorodisilane is only obtained in mixtures with further oligomers, so that additional extensive separating steps are required to recover the hexachlorodisilane.
EP 283 905 discloses producing mixtures of Si2Cl6 and Si3Cl8 with SiC4 by copper-catalyzed reaction of silicon at 140-300° C. The yield of oligosilanes reaches more than 40%, based on the amount of silicon used. The above-mentioned separating steps are required to recover hexachlorodisilane.
GB 702 349 discloses the reaction of gaseous SiCl4/Cl2 mixtures with silicon compounds or silicon alloys, for example CaSi2, at 90-250° C. to obtain mixtures of perchlorinated oligosilanes. Si2Cl6 is detected in the product mixture at 40-55% by weight. Again, the separation processes mentioned are required to effect isolation.
M. Schmeisser, P. Voss, Zeitschrift für anorganische und allgemeine Chemie 334 (1964) 50 discloses that perchlorinated polysilanes are degraded by chlorine gas at 60° C. to mixtures of perchlorinated oligosilanes SinCl2n+2 (n≧2). It is only at about 200° C. or higher that the oligosilanes undergo a further reaction to form SiCl4.
E. Bonitz reports in Chemische Berichte 94 (1961) 220 and Angewandte Chemie 78 (1976) 475 that, after CaSi2 has been ground in suitable solvents, Cl2 will convert the solid material at <60° C. initially into silicon and then into chlorinated products SiClx (x<1) up to SiCl. Higher temperatures then produce soluble products SiClx (1<x<2), until finally SinCl2n+2 compounds are obtained. The oxidation of SiCl is supported by finely divided transition metals, such as Fe, Cu or Ni.
DE 1079607 and DE 1132901 disclose that grinding silicon or silicon alloys (ferrosilicon for example) with catalytically active metals or metal compounds in liquid diluents leads to suspensions whose silicon content reacts quantitatively with chlorine gas to form SinCl2n+2 (n≧2). The oxidative cleavage of perchlorinated polysilanes with chlorine gas at temperatures that are not too high, therefore, is a suitable way to obtain mixtures of perchlorinated oligosilanes in high yields, based on the amount of silicon used. Although (Si2Cl6) is the main constituent in these mixtures, the mixtures however also contain the other oligosilanes in proportions of typically >25 wt. %, so that, as mentioned above, extensive separation processes are required to isolate the hexachlorodisilane.
The E. Bonitz approach presupposes an activation, viz., a technically laborious, intensive grinding of the silicon-containing starting materials with the addition of liquid diluents and, furthermore, the use of catalytically active metals or metal compounds.
In addition, the present disclosure provides a chimney tray having an array of chimneys, which enables a reactant to be uniformly and appropriately distributed to a catalyst bed.
It could therefore be helpful to provide a method for producing hexachlorodisilane in a particularly simple manner and a particularly high yield, based on the amount of silicon used.